There have been two deaths in the UK potentially linked to vaping, the healthcare products regulator has said.
The Medicines and Healthcare products Regulatory Agency (MHRA) said it had received two reports of e-cigarette or vaping associated lung injury (EVALI) in which the patients had died.
The regulator added that it had also received 20 reports describing 27 "serious respiratory events" linked to e-cigarettes, including pneumonia and lower respiratory tract infection.
Public Health England (PHE) said the deaths were "concerning" and it follows an outbreak of vaping-related illnesses in the US which had led to 60 deaths.
Professor John Newton, director of health improvement at PHE, said: "These two deaths are concerning and we await the outcome of MHRA's investigation.
"We have also been working with the MHRA to be sure that any cases of respiratory illness linked to e-cigarettes are correctly identified and reported.
"The US outbreak has been strongly linked to people vaping illicit liquids containing Vitamin E acetate.
"We have not however seen a similar outbreak here in the UK."
The World Health Organisation (WHO) said earlier this month that both tobacco products and e-cigarettes "pose risks" to health and the "safest approach is not to use either".
The MHRA said cases should be considered "probably" linked to e-cigarette use or vaping if the patient had used an e-cigarette or vaped in the previous 30 days and had pulmonary infiltrates on an X-ray and an absence of respiratory infection and there was no evidence of alternative diagnosis.
The US Centres for Disease Control and Prevention (CDC) and its public health partners were investigating cases of lung injury associated with the use of e-cigarette or vaping products, the MHRA added.
More than 2,600 US cases had been identified but the outbreak seemed to be in decline, it added.
The regulator said that while the CDC had identified Vitamin E acetate as a chemical of concern, Vitamin E was not permitted as an ingredient in e-cigarettes or e-liquids in the UK.
It is estimated that 3.6 million people use e-cigarettes in the UK.
